This invention relates to a novel method of preparing carboxylic acids and particularly to the preparation of carboxylic acids from salts of nitroketones.
Nitroketones can be converted to carboxylic acids by contacting with aqueous sodium hydroxide or refluxing in sodium acetate. The method requires isolation of the intermediate and acidification to convert the intermediate sodium carboxylate to the acid. In another method involving the refluxing of nitroketones in aqueous ammonium hydroxide, there resulted a mixture of carboxylic acids and amides. U.S. Pat. No. 3,415,856 describes a method of preparing carboxylic acids by contacting the nitroketone with water in the presence of an acid such as a mineral acid, a hydrocarbon sulfonic acid or a haloacetic acid, and where the method produces two distinct carboxylic acids. While yields of 60 and 70 mole percent of monocarboxylic acids are indicated as provided by the method, there still remains substantial room for improvement. We have now found a method whereby carboxylic acids can be produced in yields as high as 90 percent and greater, which method also provides as a valuable coproduct a nitroalkane.
It is, therefore, an object of this invention to provide a method for the preparation of carboxylic acids in high yields.
Another object of this invention is to provide a method for the preparation of carboxylic acids from salts of nitroketones in the absence of forming substantial amounts of by-products such as amides.
Yet, another object of this invention is to provide a method for converting a salt of a nitroketone to a carboxylic acid and a nitroalkane.
Other objects and advantages will become apparent from a reading of the following detailed description and examples.